Borrelia recurrentis causes louse-borne relapsing fever (LBRF). LBRF is transmitted from person to person by the body louse. Tick-borne relapsing fever (TBRF), a zoonosis usually transmitted from rodents to humans via the bite of various Ornithodoros ticks, is caused by multiple Borrelia species. DNA rearrangement within vmp genes on linear plasmids results in variation in expression of surface antigens, allowing evasion of host immune responses.